Websocket API questions

WebThings
#1

I read the Websocket API here https://iot.mozilla.org/wot/#web-thing-websocket-api
I have two questions:

  1. Is this Websocket API implemented on the gateway?
  2. If yes, can I connect to a single WS endpoint and read/write from/to all devices? As I see from the specs, it is expected to create a new WS connection for each device. If we have 100 devices in the gateway, that means 100 simultaneously opened WS connections in order to get real-time state updates in some 3rd party app (e.g. a UI). This is not good.
#2

Yes. You can see implementation here.

No.
I think it would be nice if we could pick up all events with a single websocket as you say. However, even if this is implemented, it probably will not be written at https://iot.mozilla.org/wot/.
It seems that wot API is focusing on a single thing interface. On the other hand, the gateway implements interfaces for things in addition to the wot API to handle multiple devices. For example, GET /things gets descriptions of all devices on the gateway.

#3

Thanks for that answer. As I see, we have a problem here interacting real-time with more than one device. If I want to create a 3rd party UI app now, I need to open a lot of WS connections to the gateway, each for each device in it. That may not be even technically possible, as browsers implement limitation for simultaneously opened connections. I see that this implementation is by WOT specification, but WOT was meant for a single device purposes, while gateway is meant to cover many devices underneath. So maybe its worth thinking about another interface that is gateway specific, not WOT specific?

#4

Yes that is the API implemented by the Things Gateway and yes it is currently necessary to open one WebSocket per Thing, using the Thing’s URL. I do think we should add the ability to have multiple Things per WebSocket, we may just need to add a thing ID (URI) to each message. See https://github.com/mozilla-iot/wot/issues/46

The Web Thing API is intended for both individual devices and for gateways which expose the Web Thing API for multiple devices.